DESCRIPTION: Merlin is a member of a family of proteins that link actin-based cytoskeleton to integral membrane proteins. Loss of merlin function (in familial and sporadic neurofibromatosis (NF) type 2) precipitates the formatio of slow-growing schwannomas or meningiomas on the vestibular nerve; either the tumor or surgery to remove it may cause deafness. A means of compensating for the loss of merlin could provide a way to stop or slow tumor growth. Merlin i similar enough in sequence to the other family members that it likely performs the same general function, but exactly how it acts to control cell division an prevent tumor formation is not now understood. The investigator proposes to identify the proteins with which merlin normally interacts. The application aims to accomplish this by (i) interaction trapping, to identify human fetal brain cDNA segments whose products bind in yeast cells to a merlin "bait"; (ii use of radiolabelled merlin protein, to probe a library of expressed mouse embryo cDNAs and (iii) immunoprecipitation of merlin under conditions designed to coprecipitate any other proteins bound to it. Experiments are designed in which the cDNAs encoding candidate merlin-interacting proteins will be tagged with an epitope recognized by available antibodies, and then expressed in cell In vivo testing of the interaction of the tagged proteins with merlin is to be attempted by coimmunoprecipitation from cell lysates, while in vitro testing i to be attempted by binding to a merlin fusion protein. Preliminary in vitro results have confirmed an interaction between merlin and merintc, an isolate from the interaction trap screen. The investigator proposes to test the in vivo interaction between merlin and full-length tagged merintc by coimmunoprecipitation and evaluate the biological role of interacting proteins.